1. Field of the Invention
The present invention relates to a wide-band antenna and a manufacturing method thereof. More particularly, the present invention relates to a wide-band antenna for transmitting wireless communication network signals and a manufacturing method thereof.
2. Description of the Related Art
With the progress of science and technology, human's technology in wireless communication keeps progressing. In recent years, a variety of wireless communication network technologies and standards have been continuously released, which includes, for example, the Wi-Fi wireless network standard defined in IEEE 802.11 by IEEE earlier and the Worldwide Interoperability for Microwave Access (WiMAX) standard defined in IEEE 802.16 lately. Therefore, the quality and the quantity of wireless communications are both improved enormously. Especially for WiMAX, the transmission distance has been increased from meters to kilometers, and the bandwidth becomes wider over the prior art.
In order to comply with the progress of wireless communication network technology, the antennas for receiving/transmitting wireless signals therefore need to be enhanced. FIG. 1 illustrates a conventional dual-frequency antenna which is disclosed in U.S. Pat. No. 6,861,986. This dual-frequency antenna includes a first radiator 31 and a second radiator 32, both connected to a ground surface 4. Signals are fed through the core conductor 61 directly to excite the first radiator 31 to form a high frequency mode with a center frequency of 5.25 GHz. The direct-feed-in signal can also excite the second radiator 32 to form a low frequency mode with a center frequency of 2.45 GHz. Besides, the length of the second radiator 32 is about a quarter (¼) of a wavelength at its operating frequency.
The antenna is fed with signals by the direct-feed-in with a bandwidth of about 200 MHz in the low frequency mode, and accordingly, the demand for wider bandwidth of WiMAX can not be fulfilled. Moreover, for compliance with the operating frequency of the low frequency mode, the length of the second radiator 32 can not be reduced to accommodate the demand for miniaturization of electronic devices.